1. Field of the Invention
The present invention relates generally to devices for securing a circuit board to a socket for electrical connection. In particular, an exemplary embodiment of the present invention relates to a clamping device for securing a circuit board within a socket of a computer bus.
2. Background
FIG. 1A illustrates a conventional circuit board 100 situated for placement into a connector socket 140 located on a baseboard 110, such as a “motherboard”, of a computer. The circuit board 100 includes circuit elements 120 (i.e., processors, resistors, capacitors, or the like) and can also include one or more plug connectors 160 for external connection connected through a mounting bracket 150. The typical circuit board 100 includes one or more connectors 130 and 130′ (connector 130 shown with electrically conductive leads 135) shown slightly elevated from the connector socket 140 (hereinafter “socket”) which is the mate for connector 130. While connector 130′ is shown as a pronged connector, other types of connectors could also be employed.
FIG. 1B shows an end view of the conventional circuit board 100 shown in FIG. 1A, with the circuit board 100 (shown in dashed lines) and associated connector 130 (not shown) inserted into the socket 140. Specifically, this view illustrates how the additional connector 130′ is able to provide additional circuit connections. A connector 170 can be connected to the connector 130′ and provided to other elements in the computer via a ribbon cable or the like.
Proper positioning of circuit boards, like the one illustrated in FIGS. 1A and 1B, firmly within sockets of computers is vital to efficient operation of the computer. Normally, a plurality of circuit boards, such as interface cards, are placed as securely as possible, into sockets (i.e., electrical connectors) that are electrically connected to other elements within the computer that enable the computer, via a communications bus or the like, to properly operate. Nearly all computers have numerous sockets that enable manual placement of various circuit boards within the computer. The plurality of sockets allow, for example, a computer owner to “upgrade” a computer's processing capability, modem, display capabilities etc., by merely exchanging one circuit board for a newer updated circuit board.
While the use of numerous sockets enables an efficient and cost effective way of upgrading a computer, this increases the possibility of computer malfunction due to improperly seated circuit boards. For example, a circuit board can become lose due to vibration or shock and be damaged or fail to achieve reliable electrical connection.
Additionally, the constant miniaturization processing chips and thus the reduction of the space required for PC boards has positive spatial effects but can lead to problems associated with excessive heat generation by components. With regard to circuit boards, the constant heating and cooling of the circuit boards, especially in the continual reduction of space for placement of circuit boards, leads to the loosening of the fit of the board in the socket. As a result, even a minor movement of the computer can cause disconnection of a circuit board and malfunction of the computer. Finally, as more components are placed on PC boards, the length of the board is often extended. Accordingly, the weight of the board can cause a torque on the card that tends to cause the card to be unseated from the socket.
There have been numerous attempts to solve such problems through the employment of a support mechanism to reduce the chances that the circuit board will break off at the connector or fall out of positioning within the socket. For example, U.S. Pat. No. 5,383,793 to Hsu, discloses an adjustable height and position retainer for releasably retaining a printer circuit card in a circuit card edge connector. The retainer comprises an elongated base member for attachment to the side of a circuit card edge connector, an elongated retaining post, and a clamp assembly slideably attached to the retaining post and positionable at any selected position along the length of the retaining post.
This device however, is impractical for several reasons. For example, the device includes a base having separate pieces. This reduces the effectiveness of the card retainer in several ways. Initially, as indicated by the open ends in the elongated base member, this can lead to the post falling away from the base thereby rendering the retainer ineffective. Additionally, since the post is moveable with regard to the base, ineffective retaining of the circuit board can result, if for example, the post is installed in a non-orthogonal manner with respect to the circuit board. Moreover, the device is very complex and is not easy to use. For example, the clamping device requires at least two fingers of a hand to properly release the clamping device as two levers are required to be released from separate sets of teeth.
U.S. Pat. No. 5,996,962 to Chang discloses card retainer having a holder body including a slot which rests against an outer edge of a circuit board. The holder body has a channel into which a post is inserted. The post has a series of teeth which form a ratchet with a pawl. A pair of leaf springs having a head is attached to the top of the post. The leaf spring provides an outward bias to the head against the inner surface of the central processing unit cover which urges the circuit board to the edge connector. To assure that the holder body stays in a desired position on the circuit board, a pair of tie down straps which pass through the holder body and around the inside of the circuit board are provided. This device, like the device described in U.S. Pat. No. 5,383,793, has deficiencies in that it provides a complicated and mechanically intensive device to restrain circuit boards. For example, this device relies upon the cover for securing a circuit card. Any movement (i.e., through shifting, buckling or bending) of the cover impacts effectiveness of the card retainer.
U.S. Pat. No. 5,603,628 to Schapiro, Jr. discloses a card retainer device which utilizes a pair of tie members which connect to anchors located on or attached to the card housing bus. The anchors can be fabricated directly into the bus connectors into which computer cards are contemplated to be installed. This device also has several disadvantageous effects. The retainer device requires a special connecter having catches to secure an end of the card retainer device. Additionally, the device is difficult to pull tight between boards that are closely arranged. Moreover, the edge of the circuit board could wear against the strap and cause damage to both the card and the strap.